fix: anchor stopwords - remove generic question patterns causing cross-topic contamination

- Add ANCHOR_STOPWORDS set in anchor.py (真正通用的疑问pattern)
- Filter Chinese n-grams against stopwords in extract()
- Update sparse.py content_words extraction to use stopword-filtered query
- Diagnosis: 'Git rebase vs merge' query now correctly excludes Redis/asyncio blocks
- Phase1 results: Full CGK 42.6 tokens avg, 0% contamination (vs Last-5 67.6 tokens, 100%)
- Phase2 ablation: Gate-only accounts for most of the benefit
- Phase3 sensitivity: OVERLAP/NEW_RATIO thresholds insensitive on clean data;
  RECENT_WINDOW is the primary token budget control

Known honest limitations:
- Test set is clean 4-topic synthetic data (no real dirty dialogue)
- No strong baselines (BM25 ablation incomplete)
- No answer-level evaluation (only retrieval blocks measured)
- No parameter sensitivity on noisy real-world data
- Zero contamination on 5 queries is not generalizable
This commit is contained in:
Elaina
2026-04-22 22:30:18 +08:00
parent 2064eb7bdf
commit 9e44748f91
10 changed files with 1461 additions and 12 deletions

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#!/usr/bin/env python3
"""Phase 3: Parameter Sensitivity Analysis"""
import sys, os, json
sys.path.insert(0, os.path.dirname(os.path.dirname(__file__)))
from src.gatekeeper import ContextGatekeeper
def estimate_tokens(text):
if not text: return 0
chinese = sum(1 for c in text if '\u4e00' <= c <= '\u9fff')
english = len([w for w in text.split() if w.isascii()])
return int(chinese * 0.4 + english * 1.3 + len(text) * 0.05)
def measure_prompt_tokens(selected, query):
ctx = "".join(f"用户: {i['user']}\n助手: {i['assistant']}\n\n" for i in selected)
return estimate_tokens(ctx) + int(estimate_tokens(ctx) * 0.08) + estimate_tokens(query)
def evaluate_contamination(selected, target):
text = " ".join(i['user'] + i['assistant'] for i in selected)
found = [t for t in ['Redis', 'asyncio', 'PostgreSQL', 'Git']
if t.lower() in text.lower() and t.lower() != target.lower()]
return len(found) > 0
redis_qa = [
("Redis 分布式锁和 RedLock 算法有什么区别?", "RedLock是..."),
("Redis 集群环境下怎么做分布式锁?", "集群下..."),
("Redis 惰性删除和定期删除有什么区别?", "惰性删除..."),
("Redis 的过期 key 对 RDB 快照有什么影响?", "过期key..."),
("Redis 主从复制断线后如何增量同步?", "PSYNC..."),
]
asyncio_qa = [
("asyncio.Task 的 cancel 方法怎么工作的?", "cancel..."),
("asyncio.gather 和 asyncio.wait 的返回结果有什么区别?", "gather..."),
("asyncio 的事件循环怎么启动和停止?", "事件循环..."),
("asyncio.sleep 和 time.sleep 的区别是什么?", "sleep..."),
("asyncio 的 Future 对象怎么获取结果?", "Future..."),
]
pg_qa = [
("PostgreSQL 的 MVCC 机制是怎么保证读不阻塞写的?", "MVCC..."),
("PostgreSQL 的 VACUUM 为什么要定期运行?", "VACUUM..."),
("EXPLAIN ANALYZE 怎么看执行计划?", "EXPLAIN..."),
("PostgreSQL B-tree 索引和 Hash 索引的区别是什么?", "B-tree..."),
("PostgreSQL 的 TOAST 机制是什么?", "TOAST..."),
]
git_qa = [
("Git 的 rebase 和 merge 的区别是什么?", "rebase..."),
("Git reset 的 --soft、--mixed、--hard 有什么区别?", "reset..."),
("Git stash 暂存区和工作目录的区别是什么?", "stash..."),
("Git 的 bisect 怎么用来快速定位 bug", "bisect..."),
("Git 的 reflog 怎么用来恢复误删的提交?", "reflog..."),
]
TEST_SEQ = [
("问PG", "EXPLAIN ANALYZE 怎么看执行计划?", "PostgreSQL"),
("问Git", "Git 的 rebase 和 merge 有什么区别?", "Git"),
("问Redis", "Redis 惰性删除和定期删除有什么区别?", "Redis"),
("问asyncio", "asyncio.Task 的 cancel 方法怎么工作的?", "asyncio"),
("再问Git", "Git 的 reset 和 revert 的应用场景有什么区别?", "Git"),
]
def build_gate():
g = ContextGatekeeper(token_budget=4000)
for i in range(5):
g.add_turn(redis_qa[i][0], redis_qa[i][1])
g.add_turn(asyncio_qa[i][0], asyncio_qa[i][1])
g.add_turn(pg_qa[i][0], pg_qa[i][1])
g.add_turn(git_qa[i][0], git_qa[i][1])
return g
def run_with_overlap_threshold(threshold):
g = build_gate()
g.topic_gate.OVERLAP_CONTINUE_THRESHOLD = threshold
g.topic_gate.OVERLAP_SWITCH_THRESHOLD = threshold * 0.44 # ratio ~0.20/0.45
tokens, cont = [], []
for _, q, t in TEST_SEQ:
sel = g.select(q)
pt = measure_prompt_tokens(sel, q)
c = evaluate_contamination(sel, t)
tokens.append(pt)
cont.append(c)
return sum(tokens)/len(tokens), sum(cont)/len(cont)*100
def run_with_new_ratio_threshold(threshold):
g = build_gate()
g.topic_gate.NEW_RATIO_SWITCH_THRESHOLD = threshold
tokens, cont = [], []
for _, q, t in TEST_SEQ:
sel = g.select(q)
pt = measure_prompt_tokens(sel, q)
c = evaluate_contamination(sel, t)
tokens.append(pt)
cont.append(c)
return sum(tokens)/len(tokens), sum(cont)/len(cont)*100
def run_with_recent_window(window):
g = build_gate()
# Patch retrieve to use custom window
orig_retrieve = g.retriever.retrieve
def patched_retrieve(blocks, qa, top_m=20, **kwargs):
# Use smaller/larger window
if window < len(blocks):
blocks = blocks[-window:]
return orig_retrieve(blocks, qa, top_m, **kwargs)
g.retriever.retrieve = patched_retrieve
tokens, cont = [], []
for _, q, t in TEST_SEQ:
sel = g.select(q)
pt = measure_prompt_tokens(sel, q)
c = evaluate_contamination(sel, t)
tokens.append(pt)
cont.append(c)
return sum(tokens)/len(tokens), sum(cont)/len(cont)*100
def main():
print("="*70)
print("Phase 3: Parameter Sensitivity Analysis")
print("="*70)
# Baseline
g = build_gate()
base_tokens = []
base_cont = []
for _, q, t in TEST_SEQ:
sel = g.select(q)
base_tokens.append(measure_prompt_tokens(sel, q))
base_cont.append(evaluate_contamination(sel, t))
base_tok_avg = sum(base_tokens)/len(base_tokens)
base_cont_pct = sum(base_cont)/len(base_cont)*100
print(f"\nBaseline (default params): {base_tok_avg:.1f} tokens, 污染率 {base_cont_pct:.0f}%")
print(f" Default: OVERLAP=0.45, NEW_RATIO=0.70, RECENT_WINDOW=15")
# OVERLAP threshold sweep
print("\n--- OVERLAP_CONTINUE_THRESHOLD sweep ---")
for th in [0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60]:
avg_tok, cont_pct = run_with_overlap_threshold(th)
flag = " ← default" if th == 0.45 else ""
print(f" overlap={th}: {avg_tok:.1f} tokens, 污染率 {cont_pct:.0f}%{flag}")
# NEW_RATIO threshold sweep
print("\n--- NEW_RATIO_SWITCH_THRESHOLD sweep ---")
for th in [0.50, 0.60, 0.70, 0.80, 0.90]:
avg_tok, cont_pct = run_with_new_ratio_threshold(th)
flag = " ← default" if th == 0.70 else ""
print(f" new_ratio={th}: {avg_tok:.1f} tokens, 污染率 {cont_pct:.0f}%{flag}")
# RECENT_WINDOW sweep
print("\n--- RECENT_WINDOW sweep ---")
for win in [5, 10, 15, 20, 30]:
avg_tok, cont_pct = run_with_recent_window(win)
flag = " ← default" if win == 15 else ""
print(f" window={win}: {avg_tok:.1f} tokens, 污染率 {cont_pct:.0f}%{flag}")
out = {'baseline_tokens': base_tok_avg, 'baseline_contamination_pct': base_cont_pct}
out_path = os.path.join(os.path.dirname(__file__), 'phase3_sensitivity_results.json')
with open(out_path, 'w') as f:
json.dump(out, f, indent=2, ensure_ascii=False)
print(f"\nSaved to: {out_path}")
if __name__ == '__main__':
main()